Mousetrap Vehicle

1. Bro. Nigel Pratt bronigel@kellenberg.org Dennis Papesh papeshdr@holyangels.cc Mousetrap Vehicle

2. Teams will design, build, and test a vehicle which uses one or two single-spring mousetraps as their sole source of energy for propulsion. Goal

3. This is basically what you wanted to do (1986-1995) • http://www.youtube.com/watch?v=Hqc9uexNL64 • The rules were very similar to what we have had with Wheeled Vehicle and Battery Buggy in the past. • BUT THIS YEAR – EXCITING CHANGES ARE IN STORE!!! Years ago….

4. Only one or two unmodified single-spring mousetraps (not rat traps) may be used as energy sources. • Unmodified means that all the original parts of the mousetrap(s) remain in place. • Things may be added to the mousetrap(s), but not removed. • Mousetrap bases less than 6.0 cm x 12.0 cm Parameters

5. All parts of the vehicle must move as a whole, i.e. no anchors, tie downs, launching ramps, or other separate pieces are allowed. • If any piece falls off during a run, it is considered a Competiton Violation. • All of the vehicle’s kinetic energy must originate from the mousetrap(s). • Conversion of the mechanical energy of the mousetrap(s) spring is permissible, but any additional energy sources must be at their lowest states at the beginning of the run. Parameters – cont’d

6. Reversing and stopping mechanism must work automatically. • The vehicle may not be tethered or controlled in any way to guide it, reverse it, or make it stop. • Recoil is NOT considered reversing. Parameters – cont’d

7. The vehicle must have a fixed, pointed object on the perimeter of the chassis of the vehicle that extends to within 1.0 cm of the track’s surface. • Toothpick, pin, small nail • Must be easily accessible to event supervisor without lifting or moving vehicle • The tip of this fixed, pointed object nearest the track surface will be used as the reference point on the vehicle for all distance measurements. Parameters – cont’d

8. The vehicle’s wheel base is the distance measured parallel to the direction of travel between the center of rotation of the front and rear axles, and it must be between 30.0 and 34.0 cm. • The vehicle’s maximum wheel width is the distance measured perpendicular to the direction of travel between the outermost side of the left and right wheels and it may not exceed 25.0 cm. Parameters – cont’d

9. Sighting devices which do not use electricity are permitted. • Sighting devices do not have to be permanently attached and may be removed before the vehicle runs. • No part of the vehicle, other than the wheels, may contact the floor or tape defining the track at any time. Parameters – cont’d

10. The competition will be on a straight and level lane with a relatively smooth, hard, low-friction surface. • Three quarter or one inch tape will be used to define the track’s starting line, a line 7.00 meters from the starting line (the “7 meter line”), and a line 8.00 meters from the starting line (the “8 meter line”) The track

11. The same tape will be used to define the 1.50 meter lane side boundaries from the starting line to the 8 meter line. • The center of the start line will be indicated with an arrow drawn in ink pointing toward the inside tape, The 7 meter line will be likewise marked. • The distance between the two arrows will measure exactly 7.00 meters. The track – cont’d

12. Additional space must be provided in all 4 directions of the lane to allow for the vehicle over-running the track. • At the National Tournament, there will be 0.50 meters of additional space outside the lane side boundary and there will be 2.00 meters of additional space beyond the starting line and the 8 meter line. The track – cont’d

13. Every 0.5 meters of additional space beyond the 8 meter line will be marked with tape. • The additional space requirements for Regional and State tournaments will depend on the availability of the venue. • Realize that ALL levels of competition SHOULD have a similar set-up. The track – cont’d

14. The students can chose to start their vehicle anywhere along the starting line with the designated fixed point directly above the starting line. • A target may be placed at the finish line to aid in aligning the vehicle, but must be removed before starting each run. The competition

15. The vehicle must be able to remain at the starting position without being touched until the trigger is released using a pencil, pen, dowel, or similar device. • which is not a part of and does not travel with the vehicle • It is considered a run if the vehicle moves any distance after the trigger has been released. • So if it doesn’t move. It’s not considered a run. The competition – cont’d

16. The students may not push the vehicle nor will they be allowed to constrain the vehicle during release. • The fixed point of the vehicle is to cross the 7 meter line and return to the center of the starting line as quickly as possible in order to receive the maximum score. The competition – cont’d

17. Reversing and stopping mechanisms must work automatically. The vehicle may not be tethered or remotely controlled in any way to guide it, reverse it, or make it stop. • So, you can’t do this…. • http://www.youtube.com/watch?v=VO_k9Hkz_oU • Teams will have 10 minutes of Event Time in which to get two runs started. The competition (cont’d)

18. The Event Time will begin when the students are allowed to place their vehicle on the starting line. • Teams will have 10 minutes of Event time in which to get 2 runs started. The competition – cont’d

19. If the second run has started before the 10 minute period has elapsed, it will be allowed to run to completion. • Time used by the Event Supervisor for measuring will not count toward the 10 minute Event Time. The competition – cont’d

20. Teams may not follow their vehicle down the track. • They must wait until called by the Event Supervisor to observe their finish distance and pick up their vehicle. • At this point, the Event Time will resume. • Students may take any measurements and make any adjustments to their vehicle. The competition – cont’d

21. Measurements made by the Event Supervisor are the only ones that will be used as the official distances. • Teams who wish to file an appeal must leave their vehicle with the Event Supervisor. The competition – cont’d

22. The Run Score shall be the sum of the Distance Score + Lane Bonus + Over-run penalty + Time Score. • Negative scores are possible. • Low score shall be the winner. scoring

23. The Distance Score shall be the distance measured in centimeters (to 0.1 cm) from the center of the starting tape to the tip of the fixed point. Scoring – distance score

24. There shall be a -20 point Lane Bonus awarded to any vehicle whose fixed point remains inside the tape defining the 1.50 meter lane between the starting line and the 8 meter line while traveling both directions. Scoring – lane bonus

25. If the fixed point of the vehicle crosses the 8 meter line, an Over-run penalty shall be assessed as follows: • 50 points shall be added for crossing the 8 meter line • An additional 50 points shall be added for each additional half-meter of travel. Scoring – over-run penalty

26. The Time Score shall be the time of each run in seconds, measured in 0.01* seconds. • The time of the run starts when the vehicle begins movement. • If the vehicle does not reverse within 3 seconds after coming to a stop, the total run time will be the time of motion plus the three seconds. • If the vehicle reverses direction, the run time will stop when all motion ceases. Scoring – time score

27. At Regional competitions, the Time Score shall be added as 1 point for every second. • At State competitions, the Time Score shall be added as 2 points for every second. • At National competition, the Time Score will be added as 4 points for every second. Scoring – time Score cont’d

28. Outlined in Section 5 (The Competition) • Will result in being ranked in Tier 3 Scoring – competition violations

29. Construction Violations are outlined in Section 2 (Construction Parameters) • Will result in being ranked in Tier 4 Scoring – construction violations

30. Teams will be ranked in four tiers using the single run that will give them the best overall place where: • 1st Tier: A run with no violations and reverses its direction of travel • 2nd Tier: A run with no violations but does not reverse its direction of travel • 3rd Tier: A run with Competition Violations • 4th Tier: A run with Construction Violations or both Competition and Construction Violations Scoring - tiers

31. 1st Tie Breaker • Distance Score of the counted run. • 2nd Tie Breaker • The vehicle’s other run score. • If the device cannot start at least one run within the 10 minute period, or has two failed runs, the team will receive participation point(s) only. Scoring – cont’d

32. At State competition, the run took 15.8 seconds. The fixed point crossed the 8.5 meter line, but not the 9 meter line, and ended up with its fixed point 18.6 cm from the center of the starting line. It stayed within the lane the entire run. No violations. Time Score 31.6 points (15.8 sec = 15/8 sec x 2 pt/1 sec) Over-run Penalty 100.0 points (50 passed 7.5 m + 50 passed 8.0 m) Distance Score 18.6 points Lane Bonus -20.0 points Run Score 130.2 points (31.6 + 100 + 18.6 – 20) Scoring example

33. So for a basic construction: • http://www.youtube.com/watch?v=OOobN0bUxqs&feature=fvw • Things to consider and discuss • Dimensions of the vehicle • Keep in mind: KINETIC ENERGY • Mass, friction, efficiency of energy transfer • Experienced coach Wisdom re: rulers • Experienced coach Wisdom re: axles So how do you make a good one?

34. Wheels • # - 3 wheeled v. 4 wheeled • Type – Rubber, balsa, plastic (DVD’s), etc… • Diameter – Should both axles have the same size wheels? • Energy Transfer: How will you transfer the energy of the spring to the axle for maximum speed? • Directly v. Indirect (spring, rubber band) • Torque issues are very important here – Axle thickness • Do you want to have the energy delivered very fast to the wheels and use momentum to travel down the course or should the energy be applied at a constant (but slow) rate to the wheels?

37. String issues • entanglement, “free string” getting caught in the axles/wheels • Type – String that stretches or doesn’t • Length of drive arm – short v. long • Please, please forgive us for the following… • http://www.youtube.com/watch?v=wZDSfRe5opo • How will you make it reverse??? • Let’s take a brainstorming session…..